amending very dry, compacted soil around a tree

I need site-specific suggestions for amending very compacted, dry soil around an existing tree. The soil is compacted because it's been lawn that's been mowed very low, plus hot temperate climate with drying winds and semi-drought summers apart from this year. Soil is silt with some organic matter but not much clay (I can do a soil in a jar test if that helps).

I'm adding a mulch basin. The plan is to use materials I have to hand to mulch on top, with a good layer of vege scraps and other organic matter and tiger worms underneath, but I feel like I need something else right on the soil to help that process of restoring the microbia. It's been forked to put holes in it but not very deep because the ground is hard, and watered well. It has couch root in it so eventually the couch will grow again. I'm not too worried about that, couch will help, and I'll be planting other things. I'm in two minds about laying cardboard/newspaper due to the risk of it drying out and becoming an impervious layer to water.

I don't want to buy in any amendments, but can utilise what is in my area as well as what is on site eg bring in animal manure. I have some half composted humanure too, that's had worms and vege scraps in it.

If you have any mushrooms in your area maybe you could make a slurry of them and spray them over the root zone. Even if they're not mychorrhiza the mycelium will still penetrate into the soil. Otherwise I think you're doing everything that I would think of.

Unrelated, but when I did a spell check of mychorrhiza and left out the second 'h' the only suggestion the computer gave me was 'horrifically' Thought that was funny.

good idea! We have Marasmius growing in the lawn already. Not sure how they would do buried deep. This makes me think I should put some well saturated cardboard down. And get some mycelium from under the mulch of local trees.

How would you suggest making a slurry? From the fruit body? It's mid summer here, so not a huge number of mushrooms around.

There are some real fungal enthusiasts around here that will probably give you an informed opinion soon. I was just thinking of putting whatever mushroom parts you can find in a blender with some water. I'm lucky enough to have a very healthy fungal network on my land.

Literally scared myself yesterday when I uncovered a stink horn that was just about to fruit. I pulled out the roots of a large crab grass and there was this huge, slimy, fleshy feeling thing that my hand hit. Ugh I dug it out and it was actually really cool, about six inches from top to bottom and shaped exactly like a bird egg.  

Hi

i have a similar issue at my parents place where they water and water and the trees are not looking very happy.

because they're not permaculture minded and only tolerate token mulching i have been trialing the following.

with a hand auger (post hole digger) dig about 4 holes as deep as you can around the drip line. with mine the handle is about 800mm-1m.

now fill all these holes with 100% semi rotted wood chips. if you only have fresh wood chips just avoid allopathic stuff where possible.

mix in a generous scoop of blood and bone or other slow release fertilizer as you fill each hole with wood chips.

when watering fill each hole just until overflowing. my 8 inch dia auger at 1m has a hole volume of 60L so with chips i guestimate about 30L

you could even use all your other methods on top of this just make sure you water in these holes as all the microbes and worms spread underground from these holes.

i call it vertical swales or stealth swales.

good luck

Heavy mulch for several years will dramatically help your soil.  Worms and other biota will decompact the soil for you, but you'll need to crate a habitat for them to thrive in.  A foot or so of wood-chip mulch, spread widely from the trunk outward (at least to the drip line) will hold moisture, cut down on soil irradiation by the sun, provide habitat for worms, promote fungal growth, and provide a source for soil carbon accumulation.

Mulch, mulch, mulch, mulch, mulch.

And then wait.

Also, stay off it when it's wet.

Karl Trepka wrote:Hi

i have a similar issue at my parents place where they water and water and the trees are not looking very happy.

because they're not permaculture minded and only tolerate token mulching i have been trialing the following.

with a hand auger (post hole digger) dig about 4 holes as deep as you can around the drip line. with mine the handle is about 800mm-1m.

now fill all these holes with 100% semi rotted wood chips. if you only have fresh wood chips just avoid allopathic stuff where possible.

mix in a generous scoop of blood and bone or other slow release fertilizer as you fill each hole with wood chips.

when watering fill each hole just until overflowing. my 8 inch dia auger at 1m has a hole volume of 60L so with chips i guestimate about 30L

you could even use all your other methods on top of this just make sure you water in these holes as all the microbes and worms spread underground from these holes.

i call it vertical swales or stealth swales.

good luck

This is a great idea, one I will try on another tree on its own I think (have to find an auger to borrow, and then see if it will work in this soil). What do you think about using sawdust from a urine toilet instead of woodchips?  How often do you water the holes?

Marco Banks wrote:Heavy mulch for several years will dramatically help your soil.  Worms and other biota will decompact the soil for you, but you'll need to crate a habitat for them to thrive in.  A foot or so of wood-chip mulch, spread widely from the trunk outward (at least to the drip line) will hold moisture, cut down on soil irradiation by the sun, provide habitat for worms, promote fungal growth, and provide a source for soil carbon accumulation.

Mulch, mulch, mulch, mulch, mulch.

And then wait.

Also, stay off it when it's wet.

I don't have several years! I might not be here next summer, so the plan is to get enough established before then so that anything planted around the tree will survive without watering (no idea if that will work tbh), and that the mulch and compost will sustain itself.

I'd hazard a guess that even a foot of wood chips here would dry out, although it would definitely provide a barrier for the soil. Do you use fresh or aged?

Which brings me to a question I suppose. Most of the rain we get doesn't go far into the soil (a day of gentle rain the other day went in about 1 cm, and that would evaporate out again in a day or so of wind), so are trees like this not living off that rain? Or do they take it in via their leaves?

Hi Rose,

how much to water is very dependant on species, size of tree and weather you want survival or rapid growth........and the time of year.

at the very least dig down a bit once a week to see if still moist.........if you want growth i would aim for 50 liters per week per square meter of dripline area in the summer.....if the tree is huge the amount of water could be large so just go with what you can.


also micro swales could be used like feeder channels to fill the holes when it rains.......use a bit of slope......not on contour.

the problem with sawdust in a deep hole could be things getting anaerobic (no air) wood chips are nice and chunky and let air down the hole.......lets say no more than 10% mixed with chips

a smaller auger may be easier to use just use more number of holes.

Karl Trepka wrote:Hi Rose,

how much to water is very dependant on species, size of tree and weather you want survival or rapid growth........and the time of year.

at the very least dig down a bit once a week to see if still moist.........if you want growth i would aim for 50 liters per week per square meter of dripline area in the summer.....if the tree is huge the amount of water could be large so just go with what you can.


also micro swales could be used like feeder channels to fill the holes when it rains.......use a bit of slope......not on contour.

the problem with sawdust in a deep hole could be things getting anaerobic (no air) wood chips are nice and chunky and let air down the hole.......lets say no more than 10% mixed with chips

a smaller auger may be easier to use just use more number of holes.

Thanks Karl. I think I need to do some more observation about what is happening in various rainfalls. The trees are a couple of metres high, I want health over growth, esp health for the soil so that other things can grow there. They're fruit trees, planting in lawn, and need to survive on their own later without watering (which is what they have been doing). I'm thinking a couple of buckets of water a week at the moment ie summer (so maybe 20L).

A small auger is a good idea.